"Paul Remde" wrote:
I was planning on including a parachute
so it won't land hard if all the balloons pop,

I presume the parachute (or perhaps a simple cloth drogue?) would already
be deployed - it'd hang limp (most of the time) till needed.

But I don't want to do it if it is not safe, or not legal, etc. I
don't want to "take my chances" that it will be safe - unless the
risks are miniscule.

As far as I can tell it can be done legally since a SPOT allegedly weighs
only 209 gms (~7.4 oz) and the smallest surface is ~4.7 in^2, or ~1.6
oz/in^2 -- well under the 3 oz/in^2 specified by 101.1(a)(4)(i). (Numbers
extracted from the specs on the SPOT web site.)

I'd be mindful of 101.7 when determing when and where to launch. I'd launch
in clear weather and use 101.33 as a guideline (even though it isn't
applicable to such a small balloon.) So if the worst happens I'd have shown
intent to not launch in a hazardous manner.

I don't know what the probability is of it causing an accident, but I'd
guestimate it is indeed miniscule. Infinitesimal probability of a
collision, multiplied by a small amount of damage, multiplied by the
probability that small amount of damage yields fatalities.

Bottom line is I would not personally have any issue if such a balloon were
launched while I was in any sort of aircraft in the same area.